COMMON EQUIPMENT TROUBLESHOOTING
Real-world problems. Straight answers. Proven repairs.
This section covers the issues our technicians see most often across forklifts, aerial lifts, telehandlers, rail movers, and heavy support equipment throughout North Dakota and eastern Montana.
My electric forklift shows a full battery but still acts weak or throws random errors.
Common Causes:
A weak or sulfated battery can display 90 % even when it can’t carry load current. Forklift indicators show voltage, not capacity, so voltage drop under load causes ghost codes and slow hydraulics.
How We Fix It:
We load-test the battery, check specific gravity, clean connectors, and service contactors. Weak packs can be reconditioned or cycled before replacement. OEM software (Toyota, Hyster-Yale, Crown, Cat) verifies operation afterward.
My telehandler boom drifts down when parked.
Common Causes:
Usually internal cylinder bypass or a leaking load-holding valve letting oil bleed past seals.
How We Fix It:
We pressure-decay test, tear down, reseal, and hone the cylinder, then reinstall with new oil and filters.
My forklift or loader steering feels jerky or hard to turn.
Common Causes:
Air in the circuit, worn orbitrol, or collapsed suction hose starving the pump.
How We Fix It:
We check pump pressure, flush contaminated oil, replace the orbitrol or seals, bleed the system, and verify smooth travel under load.
My aerial lift won’t lift even though the engine runs fine.
Common Causes:
Low oil, plugged filter, or failed lift solenoid. On electric models, a bad platform safety switch or broken wire in the boom harness can interrupt lift.
How We Fix It:
We verify fluid level, test filters and valves through OEM software (Genie, JLG, Skyjack), and repair or replace damaged wiring with sealed Deutsch connectors.
My telehandler throws “transmission pressure” or “drive disable” errors.
Common Causes:
Plugged suction screen, weak charge pump, or faulty solenoid signal.
How We Fix It:
We check pressures and voltages, clean strainers, flush oil, and perform a hot-oil stall test.
My rail mover won’t build air pressure.
Common Causes:
Piston compressors—bad governor, frozen lines, worn rings.
Screw compressors—failed inlet valve, oil separator blockage, coupling wear.
How We Fix It:
We inspect control-air plumbing, test governors and unloaders, service oil systems, and verify timed pressure build.
My diesel engine keeps going into limp mode.
Common Causes:
DEF/DPF restriction, failed sensor, or crystallized DEF.
How We Fix It:
We run OEM diagnostics, forced regens, and perform Diesel Force on-truck DPF/EGR cleaning to restore flow.
My scissor lift only moves a few inches then stops.
Common Causes:
Faulty pothole-protector switches, tilt sensors, or low battery voltage.
How We Fix It:
We continuity-test safety switches, verify voltage to drive solenoid, clean connectors, and recalibrate with OEM software.
My skid steer overheats even with a clean radiator.
Common Causes:
Hidden debris between cores, bad fan relay, or plugged hydraulic cooler.
How We Fix It:
We separate and clean coolers, confirm fan operation, and check temperature sensors with thermal imaging.
My hydraulic hoses keep bursting near the fittings.
Common Causes:
Heat, tight bends, vibration, or reused fittings.
How We Fix It:
We build new hoses on-site using Parker 43-Series fittings, reroute for clearance, and pressure-test to OEM specs.
My aerial lift keeps beeping and won’t drive.
Common Causes:
Tilt or overload switch faults or moisture-corroded grounds.
How We Fix It:
We diagnose sensors via OEM software, clean connectors, reseal with dielectric grease, and recalibrate alarms.
My truck or trailer air brakes are slow to release.
Common Causes:
Oil/water contamination swelling seals or failed air dryer purge valve.
How We Fix It:
We drain tanks, rebuild or replace valves, service dryers, and verify equal release times.
My telehandler or loader won’t start — lights come on but no crank.
Common Causes:
Usually a bad ground, worn starter relay, or neutral-safety switch. Some Skyjack machines use a master switch outside the cab (right side). If it’s off, you’ll have lights but no crank. Also, on models with an electric parking-brake switch, the ECM won’t engage the starter unless that brake is applied.
How We Fix It:
We voltage-drop test from battery to starter, verify master, safety, and park-brake circuits, clean grounds, and confirm starter amperage and enable logic.
My forklift propane system frosts up or stalls out.
Common Causes:
Poor coolant flow, weak vaporizer, or restricted LP filter.
How We Fix It:
We test coolant circulation, pressure-check fuel, and replace or service vaporizers/regulators (IMPCO, Beam).
My electric pallet jack won’t hold a charge.
Common Causes:
Low electrolyte, unbalanced cells, or bad charger output.
How We Fix It:
We water cells, equalize, recondition, and test chargers for proper termination.
My equipment keeps blowing fuses or tripping breakers.
Common Causes:
Shorted coil, pinched wire, or moisture intrusion.
How We Fix It:
We megger-test circuits, isolate faults, replace damaged wiring, and verify fuse sizing.
My hydraulic system is noisy and jerky.
Common Causes:
Air in oil, cavitation, or restricted suction line.
How We Fix It:
We check level, reseal fittings, bleed air, test inlet vacuum, and rebuild worn pumps.
My boom or bucket drifts side-to-side during operation.
Common Causes:
Worn swing bearings or pins, or uneven cylinder pressure.
How We Fix It:
We measure backlash and pin clearances, pressure-test swing circuits, and rebuild pivots per OEM specs.
My machine keeps losing throttle response.
Common Causes:
Faulty throttle-position sensor, CAN-bus error, or broken signal wire.
How We Fix It:
We read live data through OEM software, verify signal integrity, repair harnesses, and recalibrate throttle mapping.
My hydraulic attachment is slow or won’t work.
Common Causes:
Sticking quick-couplers, low pilot pressure, or mismatched fittings.
How We Fix It:
We clean and test couplers, adjust pilot pressure, flush lines, and confirm correct flow rates.
My forklift constantly beeps even with the key off.
Common Causes:
Water intrusion in ECU or harness connectors bridging a power feed to the buzzer circuit.
How We Fix It:
We clean, dry, and reseal connectors, apply dielectric grease, and reroute harnesses to avoid moisture.
My propane forklift won’t start or runs poorly after changing the tank.
Common Causes:
LP tanks mount horizontally with a liquid dip tube. If not aligned with the locator pin, no liquid reaches the vaporizer. A loose or unlocked coupler also limits flow.
How We Fix It:
We confirm proper alignment, ensure full connector engagement, inspect for frost or blockage, and replace damaged O-rings or couplers.
My aerial lift starts from the ground controls but dies and won’t start from the platform controls.
Common Causes:
A stuck or faulty E-Stop switch on the platform or a failed control board in the platform box. The E-Stop may not release fully, or the board may lose power through the boom harness.
How We Fix It:
We verify voltage at the platform E-Stop and key switch, continuity through the boom harness, and bench-test the control board. Wiring is inspected for flex damage, switches replaced, and both stations tested for ECU communication.
The fuel gauge on my propane forklift shows full or empty, but the machine isn’t running.
Common Causes:
Many dual-fuel forklifts display the gasoline tank level, not propane. A “full” or “empty” reading can be misleading if the LP system isn’t connected to the gauge. A stuck selector valve or sender can also give false readings.
How We Fix It:
We identify the fuel system type, test sender voltage and resistance, and confirm which tank the gauge monitors. For propane systems, we verify proper tank alignment, regulator output, and lock-off valve operation.